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Idiot with coffee fetish

Discussion in 'Introductions' started by MJ74, Sep 21, 2018.

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  1. MJ74

    MJ74

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    Sep 21, 2018
    Hi, as the title of this thread indicates, I'm completely at a loss when it comes to electronics. I am trying to remedy this by learning the basics. I have two goals, firstly to be able to create small electronic circuits with my son so he gains an interest and some knowledge and, secondly, to turn a power drill motor into a slow turning drive for a coffee grinder dedicated to turkish coffee grind.

    I look forward to learning from the members here and hopefully gaining the ability to get this grinder working.

    Cheers MJ
     
  2. Bluejets

    Bluejets

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    Oct 5, 2014
    The following site might be of use to both you and your son.
    Many free books, great number of circuits and general info.
    Cheers ...Jorgo

    http://www.talkingelectronics.com/te_interactive_index.html

    Don't mind a drop of Amazon Coffee myself...when in Thailand.....that served with hot bark tea chaser and small cracker biscuits....great stuff.
     
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  3. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Welcome to EP.

    thumbs up :)

    I recommend to use gears to reduce speed. A power drill motor's speed can be reduced by e.g. a pwm drive, but that comes at a loss of power (lower speed = lower power input = lower power output).
     
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  4. MJ74

    MJ74

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    Sep 21, 2018
    Thanks Bluejets, I'll take a look. I've been watching a lot of tutorials for beginners on YouTube as well.
     
  5. Bluejets

    Bluejets

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    No worries....wish this stuff was around when I was a kid.
    We had to learn from text books that cost and arm and a leg and were many instances, way out of date.
    This site covers so much ....it's great.

    Word of warning, don't believe everything you see on youtube or instructables.
     
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  6. MJ74

    MJ74

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    Sep 21, 2018
    Thanks Harold, I thought of that but as I have been using a cordless drill held on at one third power to achieve a rpm of about 60 or so, I thought why not buy a power drill and mount the motor on a stand and then just wind back it's speed. If I can lightly hold on the drill to achieve the rpm and the torque is still sufficient then gears may, or should not be needed.

    Would it be as simple as replacing the drill's trigger with a pwm?
     
  7. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    An electronic kit ("Elektronik Experimentierkasten") may be a good starting point. Not only does (or at least should) it contain instructions and all required parts, usually an easy means of connecting the parts without soldering is included. Good for starters. Switch to breadboards like this later once you (and your son, of course) got the hang of it.
     
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  8. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    It is at least worth a try - unless the drill's motor is a brushless DC motor which will require a dedicated driver.

    Have a look at this board as an example of an inexpensive motor driver for brushed DC motors.
     
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  9. MJ74

    MJ74

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    Sep 21, 2018
    I watched and read some articles with some kids doing simple circuits with a bread board. Stuff like getting led lights to shine and a basic motor and computer set up. I think your tip of the Experimentierkasten is a good one.
     
  10. MJ74

    MJ74

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    Sep 21, 2018
    I don't think the one I had an eye on is brushless and, as we have quickly hit the limit of my knowledge with that motor driver, I'll make sure it isn't.
     
  11. Bluejets

    Bluejets

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    Assume it's dc (battery) drill...??
     
  12. MJ74

    MJ74

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    Sep 21, 2018
  13. Bluejets

    Bluejets

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    Oct 5, 2014
    That already has speed control in the trigger.
    Mains speed control of these motors is via thyristor and phase control.
    PWM is for dc battery motors etc.
     
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  14. MJ74

    MJ74

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    Sep 21, 2018
    Right. Things I have to learn.

    Hopefully I can take it apart to mount it and somehow slow the speed down enough with the existing trigger without having to physically hold it on.
     
  15. Bluejets

    Bluejets

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    Oct 5, 2014
    Leave it as is and simply rig up a screw clamp around the trigger and the handle.
     
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  16. MJ74

    MJ74

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    Sep 21, 2018
    I did have that thought but then I was taken by the desire to make it look pretty.
     
  17. dave9

    dave9

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    The motor could just be used with the drill's gearbox, but the motor is the easy part. By the time you buy parts and fabricate the grinder portion, you might as well have just bought a ready made grinder. These things do exist, so seems like a case of reinventing the wheel, except at great time lost to do so, probably for an inferior result as the world has had teams of people developing coffee grinders for over a century.

    I suppose you could buy one ready made, rip its motor out and stuff the drill motor in for the cheapest, easiest way to do this, but why?
     
  18. Bluejets

    Bluejets

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    Oct 5, 2014
    Drills such as shown have the motor and the gearbox components held in place by the casing.
    No such thing as simply pulling out the motor to use elsewhere.
     
  19. dave9

    dave9

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    Mar 5, 2017
    ^ Depends on the design, generally the gearbox has screws on the inside wall going into the end of the motor casing and those motor casing tapped holes can be used with same or longer screws to mount the motor elsewhere.

    For example that can be seen on the following diagram as two screws (a pair of part # 54). That will keep those two together, or allow mounting the motor separately, but to mount the motor and gearbox assembly outside of the drill casing you could simply fabricate a mounting plate to go around the gearbox, OR in some cases if the drill has a clutch on the gearbox, that too is fastened onto the gearbox with screws that can be removed and reused to mount the gearbox with the motor attached.

    Will it stand up to the rigours of grinding long enough to be worth doing? Given enough experimentation, it's do-able but on the first try? Probably a long road ahead to make a cumbersome steampunk looking thing that wasn't worth the bother because coffee grinders exist, and are fairly inexpensive too ~ $15 USD while a DIY grinder may take more in materials than that $15.

    0601916460_WW[1].gif
     
    Last edited: Sep 22, 2018
  20. Bluejets

    Bluejets

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    Oct 5, 2014
    That's dc .....op showed a corded drill
     
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